Apparatus for receiving or relaying electric signals.



G. W. PIERCE.

APPARATUS POR RECEIVING 0R RELAYING ELECTRIC SIGNALS.

APPLICATION FILED AUG. 5. 1913. I. I I 2.@55. Patented 001;. e, 1914.

G. W. PIERCE.

APPARATUS FOB. RECEIVING OB. RELAYING ELECTRIC SIGNALS.

APPLICATION FILED AUG. 5. 1913.

1,1 12,655. y Patented 00111914.

3 SHEETS-SHEET 2.

G. W. PIERCE.

APPARATUS FOR RECEIVING OP. RELAYING ELECTRIC SIGNALS.

APPLICATION IILED AUG.5.1913.

1911239655., Patented 00t.6,1914.

3 SHEETS-SHEET 3.

GEORGE W. PIERCE, 0F CAMBRIDGE, MASSACHUSETTS.

APPARATUS ron RECEIVING on EELAYING ELECTRIC sIGNALs.

Specication of Letters Patent.

" Patented Oct. 6, 1914.

Application filed August 5,'\1913. Serial No. 783,088.

To all :l1/mm, 'it may concern Be it known that l, Gi-io'uon lV. PIERCE, a citizen of the United States, residing at Cambridge. in the county of Middlesex and State of VMassachilsctts, have invented cei'- tain new and useful Improvements in Apparatusfor Receiving oi- Relaying Electric Signals; and l do hereby declare the following to be a full, clear, and exact description of the invention` such as will enable others skilled in the art to which it appertains to make and use the saine.

The present invention relates to apparatus for receiving or relaying electric signals, and

" more particularly to apparatus in which a gaseous conductor or conductors are utilized for amplifying the Yreceived or relayed impulses or signals.

The object of the invention is to produce an efficient and comparatively simple apparatas by means of which feeble received electric impulses may be detected and amplified into comparatively much greater impulses in an electric circuit which is directly or indircctly connected with a translating or signal indicating device.

W' ith the above object in vievv the present invention consists of apparatus for receiving or relaying electric signals hereinafter de` scribed and more particularly pointed out in the claims.

In the drawings, which illustrate the preferred embodiment of the present invention, Figure 1 is a diagrammatic view of the apparatus used in connection with Wireless telegraphy or telephony; Fig. 2 is a modification illustrating another forni of the apparatus for use in connection with wireless telegraphy or telephony; Figs. 3 and 4 are diagrams illustrating two modifications o f. the apparatus for use with Wiresignaling; Fig. 5 is a diagram showing three vapor or gaseous devices connected together; Fig. 6 is a diagram showing the .multiplicity of terminals inclosed in the same vessel; and'Fig. 7 is a modification showing a mercury arc as the ionizing means 'at the cathode.

Referring to the illustrated embodiment of the invention, andmore particularly to Fig. 1 of the drawings, the antenna 1 is connected through the primary 2 of an oscillation transformer 3 to the ground 4. The signal impulses or current waves set up in -the antenna cause corresponding oscillations in the closed secondary circuit 5 which includes a lsecondary 4 ofthe transformer'and a Condenser 6. This circuit 5, taken in con- ]unction with the antenna, may be for convenience designated as the receiving'eircuit. The receiving circuit is connected to the amplifying device through leads R1 and R2 which may be designated as receptor leads or connections because it is through them that the received impulses or oscillations are led to the amplifying device. A condenser C'is interposed in one of the receptor leads. In the construction shoivn in Fig. l the condenser is interposed in the receptor lead R2.

The amplifying device illustrated in Fig. l consists of two vapor or gaseous devices indicated generally by lVl1 and M2 which are interconnected so as to lcause the received signal impulses impressed on the gaseous de- `vice M1 to setA up corresponding impulses 1nl an electric circuit connecting M1 to M2. The impulses of this connecting circuit, in

turn, through the action of the gaseous deviceM2 set up impulses in another circuit which is connected to the translating or signal indicating device. The gaseous device M1 consists of an evacuated vessel V1, of

glass or quartz, preferably glass, in vwhich are inclosed a cathode K1', an anode A, and a screen S1. The screen S1 is preferably a grid consisting of a piece of iron or platinum Wire bent back and forth to form .a number of separated and parallel grid bars or elements. The screen may be made of apiece of open-Work Woven metallic fabric having interstices between the Wires thereof. The cathode K1 co-ntinuously emits .negative ionsI and `for this purpose it is made of a filament, preferably of tungsten, Which is heated to incandescence. A battery 10 connecte-d to the cathode filament through an adjustable rheostat 1l furnishes the current for heating the filament. The cathode filament K1, its leading-in Wires l2 and 13, the

rheostat 11 and battery 10, constitute a local heated bythe current in a local heating circuit which comprises leading-in Wires 2l and 22, an adjustable rheostat 23 and a battery 24. The screen S2 is connected by means ot a wire 30 to the anode A,. The leading-in Wires 13 and 2l of the cathodes l, and K, respectively are connected by a Wire connection 31 in `Which is included a battery B the negative pole of which is connected to the cathode Kr The closed circuit from the cathode TL, across the evacuated space to the anode A alongthe Wire 30 to the screen S2, across the evacuated space from the screen S2 to the adjacent cathode l, or anode A2 or both, and alon their leading-in Wires to the Wire 31 and t rough the battery AB, back to the cathode K constitutes a local battery circuit designated for convenience by the reference letter L. The anode A2 is connected through a lead Wire D,

to a signal indicating device T. The cathode*l K, is connected through its leading-in Wires, a battery B, and lead Wire D, to the signal indicating device T. The negative pole of .the battery B, is connected to the cathode K2. The closed circuit from the cathode K2 across the evacuated space to the anode A2, v

along the Wire D, through the signal detecting device T, along the Wire D2 through the 'battery B, and through the lead Wires back to the cathode K2 constitutes a closed local circuit which, for convenience, may be designated as the indicator circuit D. The leads D1 and D'2 since they connect the am plifyingdevice with the signal indicating device T may be termed the responder4 or indicator leads or connections.

While the operation of the apparatus is not perfectly understood, nevertheless for the sake of completeness and explicitness in the disclosure of the invention, the probable operation vvill be described and explained in accordance With the prevailing electronic theory of electricity. Therheostats l1 and 23 are adjusted until the two cathode iilaments K, and K, are heated to incandescence, in Which condition they continuously emit negative ions or electrons. The battery B, tends to set up a current inthe local )r connecting circuit L in such a direction as to cause a current of negative electricity to pass across the ionized evacuated space from the cathode K, to the anode A,. The incandescent cathode ilament K, ionizes the space 'between it and the anode A, and allows the negative current to pass between them. The result is that thescreen Sg which is connected through the wire 30 and the vessel V, to the negative pole of the battery B, is maintained at a potential negative with respect to the cathode K, which is connected to the positive pole of the same battery B. The negative charge given to the screen S2 leaks away across the vacuated space in the vessel V2, but is normally replenished by arianna conduction through the evacuated vessel Vr. The battery B2 causes a negative currentto tend to ilow from the incandescent cathode filament l, across the `evacuated ionized space to the anode A2. If the screen S2 is disconnected from the battery B, it allows the ne'ative ions to pass through its intersticcs from the cathode K, to the anode 'AT lli, however, the screen S2 is connected to the battery 13 as shown in the drawings, the screen S, by virtue of its negative charge greatly reduces the flow of ions from the cathode K, to the anode A, and thus reduces the current in the indicator circuit D. lt is obvious that, if the negative charge or potential of the screen S2 ductuatcs, coresponding current fluctuations will be caused in the indicator circuit D. Since the negative, charge on S2 -is continuously leaking oit' across the evacuated ionized space in the vessel V2 and is being continuously replenished by the negative current Flowing across `the ionized space from the cathode K, to the anode A it is obvious that fluctuations in t-he negative current'flowing from the cathode K, to the anode A, Wil cause iiuctuations in the charge on the screen S2, Which in turn will cause fluctuations 'in the current in the indicator circuit D. T he fluctuations in the negative current flowing acrossthe ionized space from the cathode K, to the anode A, is caused by fluctuations in the potential of the screen S,. The screen S, gets a negative` charge from the negative ions Y shot out from the cathode K, which strike the screen. This negative charge which the screen normally possesses, is not, however, suiiicient to prevent the flow of the negative current across the gap from the cathode K, to the anode A,. although it undoubtedly has some eiiect in preventlng the free passage of the negative ions across this space. It the potential of the screen S, is varied it is obvious that the more negative the potential of the screen S,'With respect to the cathode K the greater the action of the screen S, in preventing or damming the iiow of the currentacross from the cathode K, to the anode A,;

The potential of the screen S, with respect to the cathode K, is varied by the oscillations set up in the receiving circuit R,. The

variations in potential at the poles of the condenser' 6 are transmit-ted over 4the receptor leads R, and R2 and cause coi-responding` l" tential of the screen S2 With respect to the cathode K, cause corresponding variations in the 'atrasos current which flows-across thelap from the i cathode K2 to the anode A2.

'f-glocal'connecting circuit L and these ywaves or m'rria'tions'` in turn set up still larger curfl 'rent waves orr variations in 'the indicator 'circuit ID sojthatv 'muchmoreener 'is' availn'ble for cpeating' 'thesignalf indicating de- 1 '/vice T tln'fisfreceived'bythe receiving circuit.'l 2 'With' these'e'ectsthere is combined a -rectifying action at tliescreens.

' Infpractice2the vlta'geof the batteries'3B2 Aand B2 dependsfupon 2 the ,degree of exhaustion inthe vessels V2 and V2 andalso'upon [the distanceI `between the cathodes and anodes and screens 'in said vessel and 'also probably upon the size of the mesh of the screens. The cathode, anodey and screen are preferably as close together as practicable,

for example, from two lto eight millimeters apart. IVhile the voltages of the batteries B1 and B2 have to be adjusted, it has been 'found thatthe battery B2 may be in the neighborhood of about tive volts, While the battery B2 -is lin the neighborhood of about fifty volts. The battery B2 should be of suffcient voltage to cause a considerable our# rent to iiow through the detector circuit D when the screen S2 is disconnected from the lead vvire 30, and the battery B2 should be of sutlicient voltage to normally maintain the screen S2 at a potential sufficiently negative With respect to the cathode K2 to very materially cut down the current in the detector circuit `D. While the vessels V1 and V2 may be exhausted to about the same degree, nevertheless itis preferable to maintain the vessel V2 at a higher degree of exhaustion than the vessel V2. In practice it is found convenient to introduce la small4 quantity of mercury into the vessel V2 and then to exhaust the vessel by a Gaede molecular pump by means of whichthe exhaustion is carried out until the absolute pressure Within the vessel V2 is the vapor pressure of the mercury in contact with the liquid mercury. On pumping the vessel it is preferred to heat the filament and -to apply heat to the vessel during the last stages of pumping to expel residual gas. IVith the vessel V2 thus exhausted, the vessel V2 is exhausted with a Gaede molecular pump, the exhaustion being preferably carried out until the absolute pressure Within the vessel V2 is less than the vapor pressure in the vessel V2.

trial as follows. VThe degree of exhaustion -of the vessel V2 is varied and the magnitude of the response in the indicator circuit D to received lsignals of standard intensity is The ex? haustion in the vessel V2 is determined by a noted and the degree of exhaustion is de^ amplifying 'wireless messages is shown. The'apparatus illustrated 1n Fig. 2

*diifersfrom-that illustrated'in-Fig. 1 in that "a common'batteryll() 'isf used to heat the cathode {i1aments1K`2- andfK2. In this modification ofthe 'app'a'ratus-the battery B2 which vmair'i'tain's the S2 at alf-negative 'po-f 'tentrial v'is'inchldedlin'the connectlon 30 be- 'tween 'the vscreen S2 and the anode A2. The

two'I wires' 116l ,and 11;7 which form the heat- 'ing circuit-for theA tufol cathode 'filaments act in'parall'elfto form part offthe'lo'cal circuit L of the batteryifB2. -'Tl1'e form of' apparatus hiillus'tratedin' vfi). has the advantage over that illustrated in Fig. -1 of 'employing but a single batter lto heat the'cathode filaments. IBymeans o :the'rheostats 118 and 119 the heating curents of the two filaments can be adjusted independently. 1

In Fig. 3 is diagrammatically illustrated a modification of the apparatus which is particularly adapted for use in connection with signaling over wires. The currentimpulses or signalscome in over the line wires 301 and through the primary 30:2 of the transformer 303.-, One end only of the transformer secondary 304 is connected to the aniphfying device by means of a single rcceptor/lead R2 between the transformer sccc-ndary and the screen S2. The transformer sets up variations of potential in the screen S2 through the unilateral connection R2. The unilateral connection is effective probably on account of the minute capacity of the Wires which act as-a substitute for a Wire connection thro-ugh a condenser of very small capacity from the unconnected end of the sccondary'304 to the cathode K2. In this connection it may be remarked that in the apparatus illustrated in Fig. 1 the condenser' (J may have a very small capacity, or may be entirely omitted under some conditions.v It is found in practice that under some conditions, and particularly with Wire signallng, that the use of a unilateral connection from the receiving circuit to the screen S2 gives sharper signals at the signal indieating device than is the case when there is also a connection to the cathode K2.

In Fig. 4 another modification of the apparatus is illustrated. The signaling impulses to be detected come in over line Wires 401 and through the primary 402 of the transformer 403. Both of the terminals of the transformer secondary 404 are connected to the amplifying device through the receptor leads R2 and R2. In this figure the condenser C is illustrated as interposed in the receptor lead R2. So far as the successful operation of the apparatus is concerned, it is apparent-ly immaterial Whether the condenser C is interposed in the receptor lead R2 or the receptor lead R2. rllfhe signal detecting device in the indicator' circult D is' illustrated in Fig. 4 as comprising both a local indicating vapparatus 'l1 and a relaying device T2. The local indicating apparatus T2 maybe an electromagnetic relay, or the like, or a telephone connected either directly in the detector circuit D or indirectly connected, as, for example, through a transformer. The relaying device T2 may be a transformer in the case of telephony or a relay in the case of telegraphy. The relaying device T2 relays the signalson to a line wire T3 by means of which the amplilied signals may be transmitted to a distant station. The local indicating device T,L and the relaying devicevT2 may be connected in series, as illustrated, or in parallel, or one of them may be omitted. The translating or signal indicating device indicated generally by T in the other figures, and described in the claims as a signal indicating device, is intended to include both local translating or indicating devices such as any telephone or relay directly or indi` rectly connected With the indicator circuit l) and relaying devices such as a transformer by means of which the amplified impulses.

are sent to a distant station Where they are detected. n

1n Fig. 4 there is illustrated the preferred pressure regulating device fory the evacuated vessel Vl. An extension 440 of the vessel V, contains liquid mercury 441. Around the extension is a coil 442 of resistance Wire Which may be heated by electric current furnished by the battery 443. This heating current can be varied by means of the adjustable rheostat 444, or may be replaced by a cooling bath.. The vessel V, is exhausted as completely as possible, and thereafter the desired degree of pressure in it is had by varying the temperature of the mercury 441 to vary its vapor pressure in the vessel V1. By this means the pressure in the vessel may be varied until the maximum response in the local circuit L is secured.

In Fig. 5 there are illustrated the connections for three vapor or gaseous devices M M2 and M3. The cathode filaments K1, K2 and K3 are heated by a common battery 510.

The gaseous device M2L is connected with thesecondary circuit 505 of a Wireless receiving apparatus by a bilateral connection formed by the receptor leads R2 and R2, similar to the bilateral connections shown in Figs. 1 and 2, the only difference being that the con- -denser C is illustrated as interposed in the receptor lead R2. The gaseous device M1 is connected With the gaseousv device M2 by a local battery circuit L, similar tothe connection shown in Fig. 2, by means of Which the screen S2 is given momentary Huctuations in potential. The anode A2 is connected through a section of the local battery circuit L2 to athird gaseous device M3. The variavice.

intacte third gaseous ldevice between the second gas-4 eous device and signal indicating device. It is obvious that, as shown in Fig. 5, a third gaseous device, or perhaps more gaseous devices, may be connected between the second gaseous device and the signal indicating decircuit connecting the second cathode and second anode is described as being connected to a signal indicating device, it is to be understood that this is intended to include constructions like that shown in Fig. 5 in which the connection from this circuit to the signal indicating device is had through another gaseous device or equivalent interposed apparatus.

ln Fig. 6 the tWo gaseous devices M1 and M2, of which in the other figures each comprise a separate evacuated vessel, have their electrodes inclosed in a single evacuated vessel V. In place of two separate cathodes a common cathode K is employed. VOn one side of the common cathode K is the anode A, and its screen S1 which is connected to the receiving circuit. 0n the other side of the common cathode K is the anode A2 With its screen S2. The cathode K is an incandescent filament heated by the current from the battery 610. The anode A1 and screen S2 are connected in local circuit L Which includes the battery B1, by means of which the screen S2 is maintained at a negative potential. The anode A2 is connected through the battery B2 to the signal indicating device T. The form of apparatus illustrated in Fig. 6 has the advantage in that but a single evacuated vessel need be used, and the further advantage that the cathodes K2 and K2 are consolidated into a single cathode filament K. This form of apparatus has the disadvantage that it is impossible to independently adjust the pressure of the gaseous conducting space around the tivo sets of anodes and screens A1 and S2, and A2 and S2 respectively.

In Fig. 7 is illustrated a modifie-ation of the devices for ionizing the conducting space in the neighborhood of the cathode. The evacuated vessel contains the cathode K1, anode A2, and ,screen S1. The anode A, is at the top of the vessel With the screen S1 beneath it. The cathode l, instead of being an incandescent lilament, is formed by a circular plate 770 through which is a hole 771, and Which is supported over a. body of liquid mercury 772 in the bottom Therefore, when in the claims the f :s .imagens '-oflthe vessel.` In the mercury 772 is ali ironror platinum electrode 7173 which is connected to a -battery y710. fThe' battery ionizing means for the cathode. =The screen 'through a receptor circuit R1. K. 1

S, is connected with the receiving circuit The cathode is connected tothe receiving circuit by al second receptorY lead R2. Theanode-A1 is connected bvmeans of a connecting wire 730 ltoa second gaseous device, and.l the cathode K1 is connected" through a wire 731 to the second gaseous device, these external connections of the vessel being sub stantially the same as those indicated in the other figures of the drawing. The cathode may either be in' itself the source of ionization, as, for example, an incandescent filament, or the cathode may have separate provision or means'for ionizing the space surrounding the cathode; as, for example, the mercury arc illustratedin Fig. 7.

The present invention Vin its broader a'spects is not liniitedto a cathode `which in itself is the source of ionization, the essential thing being that the cathode has pro vision either in itself'or separate from it whereby the space surrounding the cathode is ionized and rendered conducting.

The apparatus ofthe present invention' is applicable for the reception or relaying or recording of an amplificationof electric signals of radio telegraphy, of radio telephony, and telegraphy and telephony over land lines and cables and over submarine cables. y

The apparatus'nuikes use of gaseous conductors as parts of its conducting circuits. By gaseous conductor is meant the re- `gion or portion of the conducting system where the ordinary metallic conductors are intercepted one from another except-for the interposition of a spacerendered partly conductive or convective for electricity7 by some ionizing agency such as, for example, the incandescent filaments or the 'mercuryarc illustrated in the drawings, Or some equivalent ion-producing agent such as an electrode maintained at a high potential, a radio-active substance, a lVehnelt cathode, a phtoelectric terminal, or similar ionizing device. Although the evacuate/d space within the vessels -is spoken of as a` gaseous conductor, it is to be understood that for some purposes everything withinv one or more of the vessels that can be removed by a vacuum pump vis removed. Under these conditions, Ian electric current across the evacuated space is, according to the prev#v -alent electric theory, 'carried by the elec trons-emitte'd from one or the other of the terminals. In addition to the conductive or convective action of the electrons from -ing the screen.

, electric charge, operates to more or less pre-- .the terminals,. a part.,-of theconductiom cr convectioncf -cu-rrent=--may be effected m some cases byfelectrons -supplled by= a residsel. The term y gaseous conductor 1s 1n G 70 tended to define' thes-space of Vregion between the terminals across which electricity is carried by conduction or. convection by means of ions -or electrons Whethery the space isl exhausted to the lastdegree poesia ble and the current-passes bythe ions or electrons' emitted from the-terminals, or the conducting ions `or electrons are'supplied from a gas in thefspaceritself.

While it is preferred torm'ake the. screens3 so 4in the form ofwire grids yas above described,

andy to have 'these'grids of about the same area as the anode plates and interposed between-4 the anode plates `and the cathode, nevertheless the construction ofthe screen;- is not limited to the preferred embodiment. It is believed that a satisfactory arrange- -ment may be had by-'making the screen of a piece of openworlrwire fabric or of a perforated plate -bent into a hollow cylinderl and surrounding the cathode, the anode being a similar and larger cylinder surround- The term screen is not intended necessarily to limit the construction of the screen to the form of a grid or..- wirefabric,but the-term screen is intended to define any conducting body which, by virtue of lits shape, its position with relation to the anode and cathode, and its vent the 'free passage of the current-carrying-ions between the cathode and anode.

As shown in the drawings, it is preferred to put a condenser in one of the receptor' leads, in order that the negative charge iin-f. parted tothe screen Sl may not have a free conducting path to the cathode K,.- The value'of the capacity of lthe condenser is best determined by experiment. t This capacity, in practice, is comparatively lsmall...110 In fact, in the construction illustrated in Fig. 3, it may be considered vthat the capacity in the receptor lead between the trans former secondary and cathode K1 is reduced to Zero. The .circuit'to which the receptor leads are connected to conduct the received impulses `tothe amplifying device is spoken of as the receiving circuit. This circuit may be the circuit'in which the oscillations are set. up in a wireless receiving station or may\ be the circuit with which the impulses are transmitted in' wire signaling. The receptor leadsmay-be connected directly to the circuit or may be connected through a trans# y, former, such as is shown, foi` example, in Figs.v 3 and 4, where thejreceptor leads are connected to the transformer secondary and are thus coupledy with'the line wire circuit.

While the preferred embodiment of `:the:

vention as particularly pointed out in the` provision for emitting negative ions, and a 4second anode and its screen inclosed in said second vessel, means for conducting signal impulses to the rst screen to vary its potential, a local circuit including a source of electromotive force and a conductive electrical connection between the first anode and seeond screen, and a 'second circuit having a connection with a signal indicating device and including a source of electromotive force and a connection between the second cathode and second anode.

2. Apparatus for receiving or relaying electric signals, having, in combination, at least one cathode having provision for emitting negative ions, an anode, a screen in proximity to the anode, a second anode, a second screen in proximity to the second anode, said elements Vbeing surrounded by gaseousconductingspace, means for conducting the electric signal impulses to the first screen to vary its potential, a local circuit including a source of electromotiveI force and a conductive electrical connection between the iirst anode and second screen, and a second circuit connected with a signal .indicating device and including a source of electromotive force and a connection between the second anode and a cathode.

3. Apparatus for receiving or relaying electric signals, having, in combination, at least one cathode, a plurality of anodesV and screens therefor, said elements being surrounded by gaseous conducting space, a receptor connection to one screen, a conductive electrical connection between another screen and an anode, and a connection from another anode and a cathode to .a slgnal ludicating device.

A. Apparatus for receiving or relaying electric signals, having, in combination, an'

evacuated vessel, a cathode, anode and Ascreen inclosed therein, a second evacuated intacta 5. Apparatus for receiving or relaying "electric signals, having, in combination, at least one cathode having provision for emitting negative ions, an anode, a screen in proximityto the anode, a second anode, a second screen in proximity to the second anode, said elements being surrounded by1^ screen, and means having a connection with a signal indicating device for causing an electric current to flow between the second anode anda cathode.

l 6. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode'having provision for emitting negative ions and an anode and its screen inclosed in said vessel, a `second evacuated vessel, a second cathode having provision for emitting. negative ions and a second anode and its screen inclosed in saidl second vessel, means for varying the potential of the rst screen in response to the repeived signal impulses, means including an Ivexternal unidirectional source of electromotive force for maintaining the second screen at a dierent potential from the sec` ond cathode andv having provision for causing variations in the potential of the second screen corresponding to variations in the potential in the first screen, and means hav- .ing a connection with a signal indicating device for causing an electric current to flow between the second anode and the second cathode.

7. Apparatus for receiving or relaying electric signals, having, in combination at least one cathode having provision for emitting negative ions, an anode and its screen, a second'anode and its screen, said elements being surrounded by gaseous conducting space, a connection to the first screen for causing variations in its potential corresponding to the received signal impulses, a local-circuit including a connection between the first anode and second screen and a source of electromotive force for maintaining a difference of potential between the second screen and rst anode, and a connection between the second anode and a cathode including a source of electromotive force.

8. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode having pro- .vision for emitting negative ions and an anode and its screen inclosed therein, `a secf ond evacuated vessel, and a second cathode having provision for emitting negative ions and an anode and its screen inclosed therein, a connection to the firsty screen for causing variations in its potential corresponding to the received signal impulses, a localcircuit including a connection between the first anode and second screen and a source of electromotive force for maintaining a second screen at a potential negative with respect tothe second cathode, and aconnection between-the second anode and second cathode including a source of electro-motive force.

9. Apparatus for receiving or relaying electric signals, having, in combination, at

vleast one cathode having provision for emitting negative ions, -a-plurality of anodes and their screens, a receiving connection to one screen, a conductive electrical connection between another screen and the anode which is adjacent the first screen, and a connection from another anode and a cathode to a signal indicating device.

10. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode having provision :tor emitting negative ions, and an anode and its screen in proximity to the cathode inclosed Within said vessel, means for maintaining the screen at a negative potential with respect to the cathode by a current supplied through a similar evacuated vessel and for superimposing on said nega# tive potential variations in potential corresponding to the signal impulses, and means including a connection to a signal indicating device for causing an electric current to iioW between the cathode and anode.

11. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode having proyvision for emitting negative ions and an anode and its screen adjacent the lcathode inclosed within saidvessel, means tending, to cause a current to iioW between the Yanode and the cathode, means including a sourceof electromotive force and a partly gaseous path for normally maintaining the screen at a potential negative with respect to the cathode, and means for causing variations in the potential of the screen corresponding to the signal impulses.

12. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode having provision for emitting negative ions and an anode and its screen inclosed in said vessel, a second evacuated vessel, a second cathode having provision for emitting negative ions and a second anode and its screen inclosed inthe second vessel, means for 'causingvariations in the potential of the first screen corresponding to the signal impulses, a circuit across the evacuated space from the first cathode to the first anode, along a wire -connection to the second screen, vacross the evacuated space from the second screen to an adjacent electrode and back along a wire connection to the `first cathode, such circuit including a source of electromotive force tending to cause a negative current to ioW from the first cathode to the first anode, and a second circuit across the evacuated space from the second cathode to the second anode, said circuit including a connection to a signal indicating device and a source of electromotive force for causing a negative current' toA iiow from the second cathode to the second anode.

13. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a cathode having provision for emitting negative ions and an anode and its screen inclosed therein, means for causing variations' in the potential of the screen corresponding to the signal impulses, and means tending to cause a current to flovv across the evacuated vessel between the cathode and anode, and a body of liquid mercury inclosed in the evacuated vwessel for maintaining a vacuum at thel desired degree of exhaustion.

14. Apparatus for receiving or relaying electric signals, having, in combination, an evacuated vessel, a 'cathode having lprovision for emitting negative ions and an anode and its screen inclosed therein, means 'for causing variaticnsin the potential of the' screen corresponding to the signal impulses, and means tending to cause a current to flow across the evacuated vessel between the cathode and anode, a body of liquid mercury inclosed in the evacuated vessel, and means for independently 4adjusting the temperature of the mercury to adjust the vapor pressure of the mercury Within said vessel.

15. `Apparatus for-receiving or relaying electric signals, having, in combination, a local circuit including a source of electromotive force, an amplifier including a plurality of electrodes surrounded by a gaseous conductor and connected with the local circuit and operating toproduce impulses in the local circuit corresponding to but of greater intensity than the received signal impulses, a second circuit including a source of electromotive force and a connection With a signal detecting device, and -a second ampliier including a plurality of electrodes surrounded by a gaseous conductor, said second amplier being conductively electrically connected vvith both circuits and operating to amplify the current impulses in the first circuit to produce impulses in the second circuit corresponding to but of greater intensity than the impulses in the first local circuit.

16. Apparatus for receiving or relaying electric signals, having, in combination, a

local circuit including a source-of electromotive vforce, an amplifier including a cathode, anode and screen surrounded by a gaseous com'luctor, said amplifier having a connection from its anode and cathode to the local circuit and a connection for leading the received impulses to its screen and operating to produce impulses in the local circuit corresponding to but of greater intensity than the received signal impulses, a second circuit including a source of electromolive force and a connection to a signal detecting device, and a second amplifier including a cathode, anode audits screen surrounded by a gaseous comluctor and having its cathode and anode connected to the second local circuit and its screen conductively electrically connected to the first local circuit and operating to amplify the impulses in the first local circuit to produce impulses in the second local 'circuit corresponding to but of greaterl intensity than in the lirst local circuit. y

17. Apparatus for receiving or relaying electric signals, having, in combination, two

` evacuated vessels cach inclosing a cathode and anode and its screen, a connectionfor leading the signal impulses to the screen in the first/vessel, a circuit including a source of electromoti've force connecting' the two vessels and including the cathode and anode in the first vessel and the screen and one of the electrodes in the second vessel, and a. second circuit connected to the anode and cathode in the second vessel, and including` a source of electromotive force and a ccnncctionl to an electric signal device, said second vessel being maintained at a greater degree of exhaustion than the first vessel.

18, The combination, with the line wire, of apparatus i'or receiving or' relaying electric signals transmitted over Wires, comprising an evacuated vessel, a cathode, anode and its screen inclosed therein, and a unilateral connection between the apparatus n'ients being surrounded by a gaseous condoctor, a connection between the cathode and anode including a source of electroinotive torce, and a unilateral connection between the apparatus and the line wire 11,1 rasee the screen.

20. The combination, with the line wire, of apparatus for receivingor relaying electric signals transmitted. over Wires, comprising` an vevacuated vessel, a cathode, vanode and screen inclosed therein, a connection between the cathode and anode including a source of electromotive force, a transformer having its primary in series with the-line wire and a unilateral connection between the transformer and the apparatus consisting of `a receptor connection from one terminal of the transformer secondary -to the screen, the other terminal of the secondary being unconnected Withthe apparatus. j

21. Apparatus electric signals, having, in combination, an anode, a screen in proximity to the-anode, a second anode, a second screen in proximity consisting of a receptor. lead connected to,\

for receiving or relaying to the second anode, means for ionizing the space about said elements, means for conducting electric signal impulses to the first screen to vary its potential, a local circuit including a source of electro-motive force and a. conductive electrical 'connection between the iirst anode'and second screen, and a. second circuit conncctedwith a signal indicating device and including a source ot' electro-motive force, and a connection between the second anode and the ionizing mea-ns. Y A

22. Apparatus for receiving or relaying electric signals, having, in combination, a cathode and an anodel and screen in proxim- .ity to the cathode, a'second cathode and a second anode and second screen in proximity to the second cathode, all the -said elements being surrounded by evacuated ionized space, means for conducting electric signal impulses to the irst screen to vary its potential, a local circuit including a source of electro-motive force and a conductive electrical connection between the lirst anode and second screen for maintain ing a ditference in potential between them, and a second4 circuit having a connection with a signal indicating device and including a source' of electro-motive force and a connection between the second cathode and second anode.

` GEORGE W. lPllERCE.

. Witnesses: i

ALICE ACKRYD, BURTON W. CARY.

t is hereby certified that in Letters Patent No. 1,112,655, granted October d 1914, upon the application of George W. Pierce, of Cambridge, Massachusetts,

for an improvement in Apparatus for Receiving or Relaying Electric Signals,. an

error appears in the printed specification requiring correction as follows: Page 2,

lines 62 and 7l, for the reference-letter B read Bf and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 10th day of November, A. D., 1914:.

[SEAL] R, F. WHITEHEAD, I 

